One example of a conventional welding apparatus of this type is illustrated in FIGS. 1 and 2.
That is, in the figures, reference numeral 1 designates a base of a welding apparatus, 2 is a movable frame transversely movable on the base 1, 3 is an entrance clamp device for holding a subsequent strip 4a, 5 is a cylinder for actuating the entrance clamp, 6 is an exit clamp device for holding a preceding strip 4b, 7 is a cylinder for actuating the exit clamp device, 8 is a welding head for welding the end portions of the strips 4a, 4b with a collected laser beam, 9 is a slide guide for supporting and moving the welding head 8, 10 is a guide for transmitting a CO.sub.2 gas layer beam from an unillustrated generator to the welding head 8, 11 is a shear device fixedly mounted on the movable frame 2, 12 is a cylinder for operating the shear device 11, and 13 is a back bar fixedly mounted on the movable frame 2 for supporting the strips.
Since the shear device 11 and the back bar 13 are fixed to a single movable frame 2 in the conventional apparatus, upon the inspection and the maintenance of the entrance and the exit clamp devices 3, 6 and the cylinders therefor 5, 7, the movable frame 2 becomes an obstacle impeding the personnel from entering between the entrance and the exit clamp devices 3 and 6, raising the disadvantages that the inspection and the maintenance of the entrance and the exit clamp devices 3, 6 and the cylinders 5, 7 are difficult.